Breakthrough X-ray system kills foodborne bugs

Barakat Mahmoud, assistant professor of food safety and microbiology at Mississippi State University, said the RS 2400 X-ray machine can eliminate E.coli,​ vibrio, salmonella, cronobacter sakazakii, shigella and Listeria monocytogenes from seafood, dairy products and leafy green vegetables such as spinach and lettuce. A method for use on tomatoes is also currently under development.

"The irradiation process, which he said is one of the first to use X-rays, takes just minutes, extends shelf-life and does not alter the visual quality of the produce. Spinach, lettuce and other fresh vegetables last 30 days longer after the spoilage bacteria are eliminated.

“The salmonella and E. coli outbreaks in fresh produce over the last few years have really brought attention to the importance of food safety,”​ Mahmoud said. “What I’ve been working on is a way to get rid of foodborne illnesses without affecting the quality and freshness of the food.”​

Even though the US Food and Drug Administration (FDA) approved the use of irradiation in 1963, a recent survey by the UK Food Standards Agency has shown that consumers remain suspicious of the technology. Mahmoud believes development of the system could help ease public anxiety over the use of irradiation as a food safety method.

“People are more familiar with X-rays than gamma rays and their use can help consumers feel more secure​”, he told FoodProductionDaily.com.

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Method​

Using the equipment is fast and simple, he said. Food items are wrapped in plastic before being placed in the machine where, after a few minutes, they are irradiated and bacteria-free.

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“The freshness of the food remains the same,”​ said the assistant professor, who is also a spokesmand for the Institute of Food Technologists. “There is minor loss of vitamins A and C, but they always are reduced in any type of food processing.”​

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Seafood​

The system could also transform post harvest treatment methods in the oyster industry - as it kills harmful bacteria but leaves the shellfish unharmed, Mahmoud said. Last year the issue of PHP treatment for oysters became a controversial one after the FDA said oyster producers should employ such methods during summer months to “substantially reduce”​ the estimated 30 deaths annually from the Vibrio vulnificus bacteria. The agency was forced to backtrack on the proposal after a storm of protest that the suggested methods would spoil the taste of the delicacy.

But the Mississippi team said the X-ray system could provide a solution to both oyster industry concerns over possible effects to the taste and food safety worries.

“We want the industry to adopt this technique as a way to make food safer​,” he said. “The technique kills all bacteria in oysters at 3-5 kiloGrays (kGy). This is amazing when you consider the FDA has approved levels up to ​5kGy for fresh seafood and 7kGy for frozen seafood. Using X-rays also means the creatures remain unharmed. This has the potential to revolutionise the PHP of oysters.”​

Commercialisation​

The team is interested in partnering with industry to scale up the system for commercialisation.

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“This technique can be effectively used in large-scale commercial operations and with the right development could be brought to market within two years,”​ Mahmoud said.